1. Do I really need Mac antivirus software?
If you never connect your Mac to the Internet, the answer is no. But if you do use the Internet, the answer is yes. And since most everyone is online these days, that means that the majority of Mac users need to consider installing Macintosh compatible antivirus software. Having said that, it is true that Macs are not as prone to malware - most Mac infections occur as a result of user behavior (downloading Warez or counterfeit software, for example). Whereas a Windows system is easily susceptible to a so-called drive-by silent infection that happens through no fault of the user, a Mac infection usually requires some deliberate (and thus avoidable) action.
2. Why are Macs less prone to infection?
Unlike Windows, Mac OS X applications don't share a common registry. Mac OS X applications use individual preference files, thus the types of global configuration changes which enable so much of Windows malware is simply not as feasible on a Mac. Further, root access is needed in order for malware to interact with other programs (i.e. steal passwords, intercept transmissions, etc.).
If you have Java enabled in your browser, it already has root access. Best bet: disable Java.
3. Are there any real Mac viruses out there?Some try to answer this question literally, based on the strict definition of 'virus' - i.e. malicious software that infects other files. But the term 'virus' is used much more loosely these days and in that context refers to malicious software in general (or what the industry terms 'malware'). The answer also depends on the version of the Mac operating system (OS) in question. While Windows tends to be essentially the same "under the hood", the various flavors of the Macintosh OS vary widely. Thus the answer to the question is Yes, there are real Mac viruses out there. But whether you are vulnerable or not depends on the OS. As for malware in general, it's an even stronger Yes.
5. Do Macs need patching?
Modern exploits target vulnerabilities in Web applications such as Java, Flash, QuickTime, and Adobe Reader. And all browsers are susceptible. Threats that run within the context of the browser or that target a Web applications such as Sun Java, Adobe Flash, Apple Quicktime, or Adobe Reader can also impact Mac users. Even if no malware is physically installed, successful exploit could be used to launch man-in-the-middle and other redirection attacks - a rising concern on the Web today.
6. What's this downstream protection I keep hearing about?
Some vendors of Mac antivirus software focus more on what is known as "downstream protection". Briefly, that's designed to protect Windows users from Windows-based malware that is sent from a Mac user. As an example, Sally uses Mac OS X 10.5 (Leopard). She receives an email with an infected attachment. That particular attachment can't infect her Mac, but if she sends it on to Bob, a Windows user, and Bob opens the attachment, his system could be infected. Downstream protection means that the Macintosh antivirus scanner is scanning for Windows-based malware.
8. What about spyware targeting the Macintosh?Spyware is a type of malicious software (malware) that monitors computer use. Depending on how over zealous the marketing is, the term spyware can refer to anything from benign cookies to dangerous keyloggers. In general, spyware is a Web threat and as such Mac users are vulnerable.
9. Can my iPod and iPhone be infected?
Yes. When Apple introduced application support for the iPod touch and iPhone, they opened the door for malware that specifically targets these devices (or, rather, the applications running on those devices). However, currently the notion of malware for these devices is more theory than reality. Jailbroken devices are more susceptible than Apple-approved devices and there have been instances of malware for jailbroken iPhones. If you plan to jailbreak your iPhone, the heightened malware risk is something to consider.